Skip to main content
ARS Home » Pacific West Area » Logan, Utah » Pollinating Insect-Biology, Management, Systematics Research » Research » Research Project #437810

Research Project: Sustainable Crop Production and Wildland Preservation through the Management, Systematics, and Conservation of a Diversity of Bees

Location: Pollinating Insect-Biology, Management, Systematics Research

2023 Annual Report

Objective 1: Improve crop pollination by alfalfa leafcutting bees, bumble bees and mason bees by identifying the environmental and biological factors that impact bee health during propagation and pollination and develop new and improved bee management strategies to ensure healthy, sustainable pollinator populations. Subobjective 1.1: Improve best management practices for pollinator use in cropping systems that result in sustainable pollinator supply for continued crop pollination. Subobjective 1.2: Identify impacts of xenobiotic factors on managed bee health (climatic factors, phenological mismatch, temperature range, etc.), host-plant [nutritional value/ host plant chemicals], invasives, pesticides. Subobjective 1.3: Examine the linkage between nutrition and bee performance in non-Apis bees (immunity, longevity, and reproduction). Subobjective 1.4: Develop effective treatments of pathogen, pest, and parasites in non-Apis bees. Subobjective 1.5. Devise new sampling and diagnostic methods for bee pests and diseases. Objective 2: Improve bee systematics and develop new tools for rapid bee identification to enhance the understanding of wild bee diversity and the identification of environmental and biological factors that promote wild bee sustainability. Subobjective 2.1: Evaluate bee biodiversity and improve the taxonomic and systematic knowledge needed to achieve effective bee conservation stewardship.

Objective 1: Improve crop pollination by alfalfa leafcutting bees, bumble bees and mason bees by identifying the environmental and biological factors that impact bee health during propagation and pollination and develop new and improved bee management strategies to ensure healthy, sustainable pollinator populations. 1.1. Hypotheses will be tested using field studies with measurement of bee health and pollination performance to improve management of mason bees and bumble bees. Experiments will examine interactions of mason with honey bees in co-deployment and impacts on pathogens as detected using molecular methods. 1.2. Exposure to agrichemicals via soil and leaf pieces by solitary bees will be quantified. The hypothesis that sublethal exposure agrichemicals including adjuvants impacts bee health will be tested for honey bees and alfalfa leafcutting bees using experimental manipulation and examine interactions with pathogens. 1.3. Hypotheses will be tested that nutrition (amino acid and sugar sources) can impact the reproduction and life span of alfalfa leafcutting bees. We will determine how the nutritional requirements of a bumble bee colony changes during colony age, as well as the maximal and minimal foraging range of Bombus huntii. 1.4. Hypotheses to examine control of chalkbrood and pollen ball formation via antimicrobial disinfectants will be tested for solitary bees. The life cycle and control of a major emerging parasitoid (Melittobia sp.) in alfalfa leafcutting bees will be determined. 1.5. Molecular methods will identify parasites, parasitoids, and pathogens of mason bees and alkali bees. Non-lethal methods to sample bumble bees parasites and pathogens will be developed. With molecular data, we will identify the species of Melittobia found in managed bees and characterize genetic diversity across populations. Objective 2: Improve bee systematics and develop new tools for rapid bee identification to enhance the understanding of wild bee diversity and the identification of environmental and biological factors that promote wild bee sustainability. We will 1) develop up-to-date taxonomies informed by phylogeny, 2) produce web-accessible bee identification tools, and 3) capture biological data present in museum specimens. To accomplish this, we will continue our efforts to survey bees across the western U.S, digitize bee collections, and conduct systematic studies of groups in need of revision. We will use molecular data, especially phylogenomic information derived from DNA sequences using ultra-conserved elements, to build phylogenies and refine species boundaries. The sequence information will be combined with taxonomic keys and images to allow non-experts to more easily identify bees.

Progress Report
ARS scientists at Logan, Utah, have reported research on solitary bees, bumble bees, and honey bees of relevance to the general public, alfalfa seed producers, almond growers, fruit growers, bumble bee producers, honey bee keepers, tomato producers, and agencies such as: Animal and Plant Health Inspection Service (APHIS) Plant Protection and Quarantine Program, U.S. Forest Service (USFS), Natural Resources Conservation Service (NRCS), U.S. Fish and Wildlife Service (FWS), Bureau of Land Management (BLM), National Parks Service (NPS), U.S. Geological Services (USGS), and U.S. Environmental Protection Agency (EPA). Expertise has been provided to private citizens and to non-profit conservation groups such as Xerces Society for Invertebrate Conservation and North American Pollinator Protection Campaign. With increased focus on native bees, ARS scientists in Logan, Utah, have actively collaborated in native bee surveys. At each location, sentinel colonies of native bumble bees and solitary bee nests were monitored at the apiary and a non-apiary site located 5 km away. For Sub-objective 1.1, progress was made using Blue Orchard Bees (BOB) in crop production. Surveys of Washington State Fruit growers had a 50% increase in the number of growers using BOBs and considering using BOBs for pollination of cherry and pear trees, given the success of previous studies. ARS researchers are studying BOB populations sourced from different states to see how they are able to adapt to the changing climate. Specifically, the researchers are looking at how well BOBs are able to emerge early to pollinate California almond orchards based on warming temperatures. In 2023, poor weather dominated most of almond pollination, but BOBs were able to double the flight time of honey bees and were able to fly at temperatures as low as 40°F. For Sub-objective 1.2, experiments continued on impacts of organosilicone spray (OSS) adjuvants. OSS adjuvants are widely used in most crops in tank mixes and can be detected in pollen. In collaboration with ARS researchers in Davis, California, and Baton Rouge, Louisiana, OSS adjuvants were found to negatively impact the egg laying of honey bee queens and increase the titers of Deformed Wing Virus in workers when fed to the workers at concentrations found in pollen. Collaborations with researchers at Utah State University have revealed how pesticides can move from soil or leaf pieces into pollen provisions. Data will allow for parameters for this exposure to be incorporated into models that are currently used by agrochemical companies and Environmental Protection Agency (EPA) to estimate the exposure of non-Apis bees to pesticides. For Sub-objective 1.4, research on treatment of pathogens and parasites continues. Alfalfa leafcutting bees are essential pollinators of alfalfa seed crops. A tiny parasitic wasp (Melittobia) has disrupted managed ALCB incubation with devastatingly high losses of bee stocks. Even if the wasps occur in a low percent of cocoons, they can move quickly into nearby cocoons and cause high losses. New best management practices for control of this wasp and other types of parasitic wasps includes moving bee stocks to cold-over-winter storage by mid fall and including a dichlorvos pesticide strip during incubation when bees are being warmed for summer emergence. If the strip is removed before bees emerge, no impacts were found on the bees and their performance. Molecular genetics were done on the wasp, resulting in a definitive ID as M. acasta. For Sub-objective 1.5, towards defining pathogens and their identifications, additional research has been performed on the microsporidian pathogens of Blue Orchard bees. Previously, a high percentage of diapausing adult bees were found to be infected with microsporidia. Sequences confirmed one of the species as related to Nosema ceranae and the other sequences were an unknown microsporidia species. In a controlled experiment, BOB larvae were fed spores of Nosema ceranae and followed through to adult emergence. The bees fed Nosema ceranae had increased mortality throughout development. OSS exposure to the bees did not increase the mortality caused by the microsporidian. For Sub-objective 2.1, much research has been performed. PIBMSRU is the home of the U.S. National Pollinating Insect Collection (NPIC), a world-class research collection of bees and related wasps with over 1.9 million specimens. NPIC also has an associated database that has information for specimens, including plant/pollinator associations. Using the database, efforts are underway to create a website on the USDA page for depicting the distribution and occurrences of bee species over time in the continental United States. The website will make the data more available to the public and to stakeholders. Several different groups of bees and their classification and phylogeny have been revisited and the work is proceeding. For the long-horned bee tribe Eucerini, ARS researchers and academic collaborators from Brazil and Israel sampled genomic data from over 153 species to examine the group’s taxonomy, phylogeny, and biogeography. The researchers improved the taxonomic resolution and understanding of this group’s evolution. The long-horned bee tribe Eucerini includes over 750 species and are important pollinators of wild and agriculturally important plants, such as squash and relatives. Two major projects have been initiated with collaborators in ARS and universities. In collaboration with Kansas State University researchers, ARS researchers in Logan, Utah, are helping to further develop state-of-the-art methods in computer vision and artificial intelligence to perform species-level bee identification. The “Beenome100” is a research effort to produce high-quality genomes of at least 100 bee species, capturing the diversity of bees in the United States. ARS researchers at Logan, Utah, are joining other ARS and university researchers to perform this research, by helping to guide species selection, collection of specimens, and data analysis. Currently, over 101 species have been submitted for sequencing. The selected species represent taxa that are essential for pollination in agriculture and natural ecosystems in the United States. Data analysis is in progress, with some genomes now available. For bumble bee species of concern, museum specimens were used to construct a high-quality reference genome for the western bumble bee and the rusty-patch bumble bee. Additional genetic studies were done for the western bumble bee and recent declines in genetic diversity was found. In collaborative studies, the decline of the western bumble bee was found to be linked to climate change and pesticide exposures. New surveys of bees have been initiated with the USFWS, asking if methods for non-lethal take can be used. Molecular identification of bees will be attempted using both collection of bee fecal material and eDNA from artificial flowers with known bee visitors. Image analysis will also be used, taking close-up images of bees and incorporating AI recognition. The Mojave Poppy Bee was found pollinating the rare Dwarf Bear Poppy (Arctomecon humilis) in Utah and later in 1995 in Nevada on the rare poppy Arctomecon californica. Since 1995, Mojave poppy bees appear to have experienced severe declines in Utah. Four surveys prior to 2020 for this bee in Utah lacked detection and resulted in the conclusion that the bee maybe locally extinct in Utah. Surveys in 2020 at multiple sites in Nevada did find the Mojave Poppy Bee on several populations of the rare poppies. Several male specimens were collected to generate a genome for the bee as part of the Beenome 100 project. In 2021 and 2022, in extensive surveys in areas under extreme drought conditions, poppies were found blooming and being visited by other bee species. However, no Mojave Poppy Bees were detected. In 2023, with abundant winter and spring precipitation, the bee species was detected in several areas that previously lacked detection. This finding raises the question of how the bee species can undergo extended diapause and emerge when weather is favorable. For the poppies, there was no evidence for limitation in pollination, with all seeds fully developing in flowers in 2022. To understand interactions between species and the potential impact of placement of honey bee apiaries on endemic native bees, controlled experiments have been performed in the Uinta-Wasatch-Cache National Forest. With a collaborator, permitted apiary sites were used at 3 locations for 3 years. For all locations, endemic native bees were sampled along with floral counts. The native bees and floral resources are being identified to species. No negative impacts on reproduction, survivorship, nor floral choice were observed because of the honey bee apiaries.

1. Western bumble bee decline linked to climate change and pesticides use. The historically abundant western bumble bee was developed commercially to deliver key pollination services to diverse cropping systems, especially greenhouse tomatoes. However, a pathogen outbreak of commercially produced populations of western bumble bee halted their production indefinitely. In addition to pathogen pressure, ARS researchers in Logan, Utah, and collaborators demonstrated in a 2023 study that the decline of wild populations of western bumble bees are linked to increasing drought conditions and pesticide use in the western United States. The results of this study will support U.S. Fish and Wildlife Service and state agencies in making informed decisions on the management of western bumble bee habitat.

2. Molecular data from museum specimens reveals declining genetic diversity in the western bumble bee, a species of conservation concern. Bombus occidentalis is an important bumble bee species that has decreased in abundance across its range in the western United States since the mid-1990’s. The species is currently under consideration for listing under the Endangered Species Act. Updated population genetic analyses to assess the genetic resiliency of the species, and its close relative B. mckayi, are needed to inform conservation decisions. ARS researchers at Logan, Utah, and collaborators at Utah State University, Ohio State Unviersity, the U.S. Fish and Wildlife Services, and other agenciess, used museum specimens collected between 1960 and 2020 to examine genetic structure and diversity in populations of B. mckayi and B. occidentalis. They found evidence of decreasing genetic diversity through time in both B. occidentalis and B. mckayi, with evidence of decline predating abundance-based measurements. Although both species have significant remaining genetic diversity, decreases in genetic diversity through time may make recovery more challenging. This work will help inform conservation decisions for the western bumble bee and it demonstrates the value of museum specimens to population genetics and conservation research generally.

3. New genomic analysis unravels the origins of bees and how they became dominate pollinators across the planet. Bees are the most important and effective pollinators of flowering plants. This interaction began about 120 million years ago, but uncertainty of how and when bees spread across the planet has greatly obscured investigations of this key partnership. ARS researchers at Logan, Utah, in collaboration with an international group of researchers, conducted a new analysis of bee biogeography, utilizing extensive genomic and fossil evidence. They confirmed that bees originated in Western Gondwana (South America + Africa) about 124 million years ago and estimated a history for how bees subsequently colonized other terrestrial habitats over time via and co-diversified with flowering plants. This information will be essential to understanding how different flowering species are linked to specific groups of bees, which is critical for conservation of those plants and their pollinators.

4. A century of sampling at a nature preserve reveals declining diversity of wild bees. Over the past few decades there has been increasing concern about the decline of wild bees around the world, often associated with loss of habitat. To test if species losses are also occurring in preserved habitats, an ARS scientist in Logan, Utah, led a team determining wild bee community change in a long-term protected nature preserve. Using museum records of bees at the nature preserve since 1921 and recent sampling efforts by the research team, they found evidence of significant community change over time, and a significant recent decline in species richness and abundance. Species losses were often associated with certain traits such as diet specialization and nesting strategy, as well as larger body size. They also found that species with more southerly ranges did well at the preserve over this period. This study provides evidence that wild bee losses are occurring in protected habitats, that certain bee traits may put species at higher risk of decline, and that community change may be driven by more widespread impacts such as climate change. In order to conserve natural areas and the plant species within, it is critical to understand which pollinators may be in danger of disappearing as the results of factors such as climate change. For growers, this information may be critical in protecting the pollinators for their crops.

5. Honey bees and bumble bees visit a wide diversity of flowers during blueberry pollination for nutritionally complete diet. Commercial blueberry production is dependent on managed bees for pollination and development of marketable fruit. Growers rent honey bee colonies as well as purchase manage bumble bee colonies for pollination. However, because blueberry pollen is low in protein, beekeepers have expressed concerns that their colonies may suffer poor health outcomes due to poor nutrition while pollinating blueberries. Therefore, an ARS scientist in Logan, Utah, led a team that collected and identified bee-collected pollen from 84 honey bee colonies and 120 common Eastern bumble bee colonies while they were on commercial blueberry farms in Michigan for pollination. Both bee species collected from a wide diversity of plants; honey bees collected from 21 plants and bumble bees collected from 29 plants, with blueberry pollen making up less than 30% of the pollen brought back to any colony. Given the diversity of pollen collected by managed bees, it is unlikely that colonies are nutritionally deprived in these landscapes and suggests that there may be other causes of poor colony performance, such as diseases, parasites, or pesticide exposure . Understanding factors impacting the pollinators is critical in ensuring their performance; in the case of blueberry fields in Michigan, nutrition can be ruled out as a factor and this study provides critical findings to both growers and bee keepers.

6. Discovery of critical lifecycle and biological traits enables control of a highly destructive parasitoid of bees used for commercial pollination. Bees have many different predators and parasitoids that can affect their populations and in turn impact the ability of growers of seed crops to have successful pollination of their crop. Among these bees is the alfalfa leaf-cutting bee that is widely used for pollination of alfalfa seed crops and canola. The tiny-parasitic wasp Melittobia can reproduce extremely quickly and wipe out entire stores of bees and disrupting crop pollination. ARS researchers in Logan, Utah, have completely determined how the wasp lives and develops in relation to the bees. Using this information, they developed methods to kill the wasp before it can cause damage and have shared these with alfalfa seed producers who depend upon these bees for successful pollination of their crops. These methods may also be applied to other species of bees that can also be parasitize, protecting many species of pollinators used for commercial pollination of nut, fruit, and seed crops.

7. Development of new genetic markers for the blue orchard bee aids in management. ARS researchers in Logan, Utah, developed 22 new genetic markers to determine the genetic health of the blue orchard bee. The blue orchard bee is an important managed pollinator of orchard crops in the United States. The new genetic markers have demonstrated their ability to capture important genetic information that may be used to make informed breeding and management decisions of the blue orchard bee. As the blue orchard bee is increasingly used for commercial pollination of fruit and nut crops, this information will be critical to bee managers and growers alike, ensure the genetic diversity of the bees and their overall performance.

8. Alfalfa leaf-cutting bees can regulate the developmental fate of their progeny in response to environmental cues. In response to climate change, bees may be able to adjust their development and responses via a type of hibernation or diapause, which is needed to survive the winter. How this is regulated had remained a mystery. ARS researchers in Logan, Utah, and their collaborators found evidence that female bees can influence the development and diapause of their progeny via mRNA transcripts that they incorporate into the eggs. The transcripts are altered in response by the female bee to changing seasonal conditions and not diet. These research findings will help enable more accurate predictions on how climate change will impact bee development and influence the availability of this important bee for pollination in the next year. This information will be critical for bee managers and alfalfa seed growers who depend upon these bees for the successful pollination of their crops.

9. Development of high-quality genome assembly of endangered rusty patched bumble bee. ARS researchers in Logan, Utah, developed the first high quality genome assembly of the endangered rusty patch bumble bee. The rusty patched bumble bee is the first bee in the continental United States protected under the U.S. Endangered Species Act. In addition to sequencing thousands of genes of the rusty patch bumble bee, ARS researchers detected genetic sequences associated with a significant bee pathogen, Varimorpha bombi. The pathogen causes dysentery, reduces mating success, and increases the chances of premature death of overwintering bumble bee queens. The results of this study will support U.S. Fish and Wildlife Service and state agencies in making informed decisions on the management of rusty patched bumble bee breeding and management programs.

10. Spray adjuvants negatively affect the egg laying of honey bee queens and viral infections in workers. Honey bee colonies depend upon a healthy egg-laying queen for colony survival and growth to meet critical pollination needs. In recent years, beekeepers have found that queen survival and performance has greatly declined. ARS researchers at Davis, California; Logan, Utah; and Baton Rouge, Louisiana, found that organosilicone spray adjuvants negatively impact the egg laying abilities of queen honey bees. In addition, workers fed the organosilicone spray adjuvants had higher levels of a pathogenic virus, Deformed wing virus. Organosilicone spray adjuvants are commonly added to tank mixes of pesticides and herbicides for application. These results support other findings that suggest these chemicals are of concern for bee health. This information has been shared by ARS with the Environmental Protection Agency, the Almond Board, and with other grower groups through the Honey Bee Health Coalition, in order to promote the usage of other adjuvants that do not have these impacts on the bees and to promote greater honey bee health.

Review Publications
Christman, M.E., Spears, L.R., Koch, J., Lindsay, T.T., Strange, J.P., Barnes, C.L., Ramirez, R.A. 2022. Captive rearing success and critical thermal maxima of Bombus griseocollis (Hymenoptera: Apidae): A candidate for commercialization? Journal of Insect Science. 22(6). Article 2.
Koch, J., Branstetter, M.G., Cox-Foster, D.L., Knoblett, J.N., Lindsay, T.T., Pitts Singer, T., Rohde, A.T., Strange, J.P., Tobin, K.B. 2023. Novel microsatellite markers for Osmia lignaria (Hymenoptera: Megachilidae): A North American pollinator of agricultural crops and wildland plants. Journal of Insect Science. 23(1). Article 1.
Janousek, W.M., Douglas, M.R., Cannings, S., Clement, M.A., Delphia, C.M., Everett, J.G., Hatfield, R.G., Keinath, D.A., Koch, J., McCabe, L.M., Mola, J.M., Ogilvie, J.E., Rangwala, I., Richardson, L.L., Rohde, A., Strange, J.P., Tronstad, L., Graves, T.A. 2023. Recent and future declines of a historically widespread pollinator linked to climate, land cover, and pesticides. Proceedings of the National Academy of Sciences (PNAS). 120(5). Article e2211223120.
Sandoval-Arango, S., Branstetter, M.G., Cardoso, C.F., Lopez-Uribe, M.M. 2023. Phylogenomics reveals within species diversification but incongruence with color phenotypes in widespread orchid bees (Hymenoptera: Apidae: Euglossini). Insect Systematics and Diversity. 7(2). Article 1.
Andrade, T.E., Ramos, K.S., López-Uribe, M.M., Branstetter, M.G., Brandao, C.F. 2022. Integrative approach resolves the taxonomy of Eulaema cingulata (Hymenoptera, Apidae), an important pollinator in the Neotropics. Journal of Hymenoptera Research. 94:247-269.
Stanley-Stahr, C.A., Pitts Singer, T. 2023. Establishmentof an olfactory conditioning assay for two solitary, cavity-nesting bees. Journal of Insect Behavior. 36:210-221.
Stanley-Stahr, C.A., Pitts Singer, T. 2023. Odor discrimination after olfactory conditioning of managed solitary bees, Osmia lignaria and Megachile rotundata. Journal of Insect Behavior. 36:180-194.
Scalici, M.B., McCabe, L.M., Alston, D.G., Pitts Singer, T. 2023. Effects of geographic origin and temperature on survival, development, and emergence of the managed pollinator, Osmia lignaria. Frontiers in Ecology and Evolution. 11. Article 1083448.
Anderson, A.R., Ramirez, R.A., Creech, E.J., Pitts Singer, T. 2023. Life cycle of Melittobia acasta (Hymenoptera: Eulophidae) using Megachile rotundata (Hymenoptera: Megachilidae) as a host. Annals of the Entomological Society of America. 116(4):207-218.
Hagadorn, M.A., Hunter, F.K., DeLory, T., Johnson, M.M., Pitts Singer, T., Kapheim, K.M. 2023. Maternal body condition and season influence RNA deposition in the oocytes of alfalfa leafcutting bees (Megachile rotundata). Frontiers in Genetics. 13. Article 1064332.
Montero-Castano, A., Koch, J., Lindsay, T.T., Love, B.G., Mola, J.M., Newman, K., Sharkey, J. 2022. Pursuing best practices for minimizing wild bee captures to support biological research. Conservation Science and Practice. 4(7). Article e12734.
Strange, J.P., Tripodi, A.D., Lindsay, T.T., Herndon, J.D., Knoblett, J., Christman, M.E., Barkan, N.P., Koch, J. 2023. Variation in North American bumble bee nest success and colony sizes under captive rearing conditions. Journal of Insect Science. 23(3). Article 10.
Spendal, R.C., Cane, J.H. 2022. Multiple daily brood cells define the fecundity of Osmia lignaria bees in a semi-natural setting. Apidologie. 53. Article 54.
Scalici, M.B., McCabe, L.M., Alston, D.G., Peterson, S.S., Yost, M.A., Pitts Singer, T. 2023. Blue orchard bee (Hymenoptera: Megachilidea) origin and orchard growing region affect female retention at artificial nest sites in cherry orchards. Environmental Entomology. 52(4):681-691.
Anderson, A.R., Ramirez, R.A., Creech, J.E., Pitts Singer, T. 2023. Mellitobia acasta (Hymenoptera: Eulophidae) female longevity and life stage-dependent parasitism using commercially managed Megachile rotundata (Hymenoptera: Megachilidae) as hosts. Journal of Insect Science. 23(3). Article 5.
McCabe, L.M., Cox-Foster, D.L., Pitts-Singer, T. 2023. Examination of hivetop incubator efficacy for emerging Osmia lignaria (Hymenoptera: Megachilidae) and the impact on Apis mellifera (Hymenoptera: Apidae) colonies. Journal of Economic Entomology. 116(2):359-367.
Koch, J., Sim, S.B., Scheffler, B.E., Geib, S.M., Smith, T.A. 2023. Chromosome-scale genome assembly of the rusty patched bumble bee, Bombus affinis (Cresson)(Hymenoptera: Apidae), an endangered North American pollinator. G3, Genes/Genomes/Genetics. 13(8). Article jkad119.
Freitas, F., Branstetter, M.G., Franceschini-Santos, V.H., Dorchin, A., Wright, K., Lopez-Uribe, M., Griswold, T.L., Silveira, F., Almeida, E. 2023. UCE phylogenomics, biogeography, and classification of long-horned bees (Hymenoptera: Apidae: Eucerini), with insights on using specimens with extremely degraded DNA. Insect Systematics and Diversity. 7(4). Article 3.